BACKGROUND & AIMS: A previously published study by our group suggested that adenoma-like dysplasia-associated lesions or masses (DALMs) in ulcerative colitis (UC) may be treated adequately by polypectomy and continued endoscopic surveillance. The length of follow-up evaluation in these patients averaged only 42 months. The purpose of this study was to evaluate the long-term outcome of our previously defined group of UC patients, all with adenoma-like DALMs, who were treated by polypectomy. METHODS: The clinical, endoscopic, and pathologic outcome of 34 UC patients, 24 with an adenoma-like DALM, and 10 with a coincidental sporadic adenoma, 28 of whom were treated by polypectomy and continued endoscopic surveillance, and 6 by colonic resection, were compared with the outcome of 49 non-UC patients who were treated similarly for a sporadic adenoma. The mean length of follow-up evaluation averaged 82.1 months and 71.8 months for the 2 UC subgroups, respectively, and 60.4 months for the non-UC controls. RESULTS: Overall, 20 of 34 UC patients (58.8%) developed at least one further adenoma-like DALM on follow-up evaluation. One patient had flat low-grade dysplasia present in the colon, which was resected within 6 months of the initial polypectomy, and another patient, with primary sclerosing cholangitis, developed adenocarcinoma 7.5 years after her initial polypectomy. There was no significant difference in the prevalence of polyp formation on follow-up evaluation between UC patients with an adenoma-like DALM (62.5%) and UC patients with a sporadic adenoma (50%), or between either of these 2 UC patient subgroups and the non-UC sporadic adenoma patient group (49%; P > 0.05). CONCLUSIONS: UC patients who develop an adenoma-like DALM may be treated adequately by polypectomy with complete excision and continued endoscopic surveillance.